JP4407024B2 - Method for evaluating plant roots - Google Patents
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【０００１】
【発明の属する技術分野】
この発明は、植物の根の評価方法に関する。
【０００２】
【従来の技術】
植物は地中に根を張り、この根から水分、栄養分を吸収して生長するから、植物の根は植物の成長に重要な役割を果たしている。昔から、植物の生育状態の良否を判断する一手法として、この根の張り具合をもって判断するという手法もある。つまり、根が植物の幹から遠くまで張っている場合には根の張り具合がよいから植物の生育状態は良好であり、逆に根の張り具合がよくない場合には植物の生育状態は不良であると判断するのである。
しかしながら、食物の根は地中にあるために地上からはその張り具合を判断することはできず、たまたま地表に根の一部が露出していれば、この露出した根と幹との間の距離から根が植物の幹からどの程度遠くまで張っているのかという張り具合を判断できるが、そうでない場合には、実際に土を掘って見なければ根の根の張り具合を確かめることはできない。このように根の張り具合は容易には確認できないという課題があった。
【０００３】
そこで、発明者は、植物の根は地中にあって、その表面は土と接触しているのであるから、植物の根と大地との間の電気抵抗というものを考えた場合に、根の張り具合が良い場合には根と土との接触面積が増加するのであるから、根の張り具合の悪い場合と比べた場合に電気抵抗が小さくなる等、植物の根と大地との間の電気抵抗（接地抵抗）を測定することにより、植物の生育状況を判断する方法を提案した（特開平１１−３３２３７７号）。
【０００４】
【発明が解決しようとする課題】
しかし、接地抵抗値は大地の比抵抗によって影響を受けるので、大地比抵抗の同じ場所における植物の根の大きさや発達状態の比較はできるが、比抵抗の異なった場所における植物の根の大きさや発達状態を正確に評価することはできない。大地の比抵抗は大地の乾湿程度などによって大きな変化を示すので、同一場所であっても雨の降った後と晴天が続いた後では異なった値となる。したがって、測定する日の大地比抵抗の値によって、根の接地抵抗値は大きくなったり小さくなったりするので、個々の根の大きさや発達状態を時間を追って正確に評価することは困難であった。
【０００５】
【発明が解決しようとする課題】
そこで本発明は、上記のような不都合を解決しようとするものであり、大地の比抵抗の変化にかかわらず、根本来の大きさや発達状態の時間推移を知ることのできる方法を提供し、さらに詳細には、根の接地抵抗と大地比抵抗を同一回路で同時に測定するための電極配置を与え、根の大きさや発達状態を数値的に評価することのできる方法を提供することを目的としている。
【０００６】
【課題を解決するための手段】
本発明に係る植物の根の評価方法は、大地に根ざした植物の茎や幹の地表から離れた部位に主電極Ｔを取り付け、前記植物から十分離れた大地に補助電極Ｃを設置し、前記植物の茎や幹の前記主電極Ｔより下方の地表付近に電極Ｅを取り付け、前記植物と前記補助電極Ｃとの間の大地の電位分布を求めて該電位分布が平坦となる領域に電極Ｐを設置し、前記主電極Ｔと前記補助電極Ｃとの間に植物を通って大地を流れる測定用電流を流し、前記電極Ｅと前記電極Ｐとの間の電圧値ＶEPを測定し、測定した該電圧値ＶEPを前記測定用電流の電流値Ｉで割って大地と前記植物の根との間の接地抵抗値ＲRを求め、前記測定用電流を流した際の、前記電極Ｐと前記補助電極Ｃとの間の電圧値ＶPCを測定し、測定した該電圧値ＶPCを前記測定用電流の電流値Ｉで割って補助電極Ｃの接地抵抗値ＲCを求め、前記補助電極Ｃの半径をａ、埋めこみ深さをｂ（ｂ≫ａ）としたとき、大地の比抵抗ρを、式、ρ＝２πｂＲC／ｌｎ(２ｂ/a)で求め、植物の根と同じ接地抵抗をもつ半球状電極の半径をｒとしたとき、植物の根の等価半径ｒを、式、ｒ＝ρ／（２πＲR）で求めることを特徴としている。
【０００７】
また本発明に係る植物の根の評価方法では、大地に根ざした植物の茎や幹の地表から離れた部位に主電極Ｔを取り付け、前記植物から十分離れた大地に補助電極Ｃを設置し、前記植物の茎や幹の前記主電極Ｔより下方の地表付近に電極Ｅを取り付け、前記植物と前記補助電極Ｃとの間の大地の電位分布を求めて該電位分布が平坦となる領域に電極Ｐを設置し、前記主電極Ｔと前記補助電極Ｃとの間に植物を通って大地を流れる測定用電流を流し、前記電極Ｅと前記電極Ｐとの間の電圧値ＶEPを測定し、測定した該電圧値ＶEPを前記測定用電流の電流値Ｉで割って大地と前記植物の根との間の接地抵抗値ＲRを求め、前記測定用電流を流した際の、前記電極Ｐと前記補助電極Ｃとの間の電圧値ＶPCを測定し、測定した該電圧値ＶPCを前記測定用電流の電流値Ｉで割って補助電極Ｃの接地抵抗値ＲCを求め、前記補助電極Ｃの半径をａ、埋めこみ深さをｂ（ｂ≫ａ）としたとき、大地の比抵抗ρを、式、ρ＝２πｂＲC／ｌｎ(２ｂ/a)で求め、植物の根と同じ接地抵抗をもつ円板状電極の半径をｒとしたとき、植物の根の等価半径ｒを、式、ｒ＝ρ／（４ＲR）で求めることを特徴としている。
【０００８】
さらに本発明に係る植物の根の評価方法では、大地に根ざした植物の茎や幹の地表から離れた部位に主電極Ｔを取り付け、前記植物から十分離れた大地に補助電極Ｃを設置し、前記植物の茎や幹の前記主電極Ｔより下方の地表付近に電極Ｅを取り付け、前記植物と前記補助電極Ｃとの間の大地の電位分布を求めて該電位分布が平坦となる領域に電極Ｐを設置し、前記主電極Ｔと前記補助電極Ｃとの間に植物を通って大地を流れる測定用電流を流し、前記電極Ｅと前記電極Ｐとの間の電圧値ＶEPを測定し、測定した該電圧値ＶEPを前記測定用電流の電流値Ｉで割って大地と前記植物の根との間の接地抵抗値ＲRを求め、前記測定用電流を流した際の、前記電極Ｐと前記補助電極Ｃとの間の電圧値ＶPCを測定し、測定した該電圧値ＶPCを前記測定用電流の電流値Ｉで割って補助電極Ｃの接地抵抗値ＲCを求め、前記補助電極Ｃの半径をａ、埋めこみ深さをｂとしたとき、大地の比抵抗ρを、式、ρ＝２πｂＲC／ｌｎ(２ｂ/a)で求め、植物の根と同じ接地抵抗をもつ棒状電極（半径Ｌ、長さＤ、Ｌ≪Ｄ）の半径Ｌを適当に定めたとき、植物の根の等価長さＤを、式、２πＲRＤ＝ρｌｎ(２Ｄ/Ｌ)で求めることを特徴としている。
【０００９】
また本発明に係る植物の根の評価方法では、大地に根ざした植物の茎や幹の地表から離れた部位に主電極Ｔを取り付け、前記植物から十分離れた大地に補助電極Ｃを設置し、前記植物の茎や幹の前記主電極Ｔより下方の地表付近に電極Ｅを取り付け、前記植物と前記補助電極Ｃとの間の大地の電位分布を求めて該電位分布が平坦となる領域に電極Ｐを設置し、前記主電極Ｔと前記補助電極Ｃとの間に植物を通って大地を流れる測定用電流を流し、前記電極Ｅと前記電極Ｐとの間の電圧値ＶEPを測定し、測定した該電圧値ＶEPを前記測定用電流の電流値Ｉで割って大地と前記植物の根との間の接地抵抗値ＲRを求め、前記測定用電流を流した際の、前記電極Ｐと前記補助電極Ｃとの間の電圧値ＶPCを測定し、測定した該電圧値ＶPCを前記測定用電流の電流値Ｉで割って補助電極Ｃの接地抵抗値ＲCを求め、前記補助電極Ｃの半径をａ、埋めこみ深さをｂ（ｂ≫ａ）、植物の根と同じ接地抵抗をもつ半球状電極の半径をｒとしたとき、植物の根の等価半径ｒを、式、ｒ＝ｂＲC／（ＲRｌｎ(2ｂ/a)）で求めることを特徴としている。
【００１０】
またさらに本発明の係る植物の根の評価方法では、大地に根ざした植物の茎や幹の地表から離れた部位に主電極Ｔを取り付け、前記植物から十分離れた大地に補助電極Ｃを設置し、前記植物の茎や幹の前記主電極Ｔより下方の地表付近に電極Ｅを取り付け、前記植物と前記補助電極Ｃとの間の大地の電位分布を求めて該電位分布が平坦となる領域に電極Ｐを設置し、前記主電極Ｔと前記補助電極Ｃとの間に植物を通って大地を流れる測定用電流を流し、前記電極Ｅと前記電極Ｐとの間の電圧値ＶEPを測定し、測定した該電圧値ＶEPを前記測定用電流の電流値Ｉで割って大地と前記植物の根との間の接地抵抗値ＲRを求め、前記測定用電流を流した際の、前記電極Ｐと前記補助電極Ｃとの間の電圧値ＶPCを測定し、測定した該電圧値ＶPCを前記測定用電流の電流値Ｉで割って補助電極Ｃの接地抵抗値ＲCを求め、前記補助電極Ｃの半径をａ、埋めこみ深さをｂ、植物の根と同じ接地抵抗をもつ円板状電極の半径をｒとしたとき、植物の根の等価半径ｒを、式、ｒ＝πｂＲC／（2ＲRｌｎ(２ｂ/a)）で求めることを特徴としている。
【００１１】
さらに本発明に係る植物の根の評価方法では、大地に根ざした植物の茎や幹の地表から離れた部位に主電極Ｔを取り付け、前記植物から十分離れた大地に補助電極Ｃを設置し、前記植物の茎や幹の前記主電極Ｔより下方の地表付近に電極Ｅを取り付け、前記植物と前記補助電極Ｃとの間の大地の電位分布を求めて該電位分布が平坦となる領域に電極Ｐを設置し、前記主電極Ｔと前記補助電極Ｃとの間に植物を通って大地を流れる測定用電流を流し、前記電極Ｅと前記電極Ｐとの間の電圧値ＶEPを測定し、測定した該電圧値ＶEPを前記測定用電流の電流値Ｉで割って大地と前記植物の根との間の接地抵抗値ＲRを求め、前記測定用電流を流した際の、前記電極Ｐと前記補助電極Ｃとの間の電圧値ＶPCを測定し、測定した該電圧値ＶPCを前記測定用電流の電流値Ｉで割って補助電極Ｃの接地抵抗値ＲCを求め、前記補助電極Ｃの半径をａ、埋めこみ深さをｂ（ｂ≫ａ）、植物の根と同じ接地抵抗をもつ棒状電極（半径Ｌ、長さＤ、Ｌ≪Ｄ）の半径Ｌを適当に定めたとき、植物の根の等価長さＤを、式、ln（２Ｄ／Ｌ）／Ｄ＝ＲRｌｎ(２ｂ/a) ／（ｂＲC）から求めることを特徴としている。
【００１２】
【発明の実施の形態】
以下本発明の好適な実施の形態を添付図面に基づいて詳細に説明する。
発明者は、樹木と大地間の電気抵抗を接地抵抗の形で測定し、ひとつの樹木の接地抵抗の変化を日を追って測定した結果、その値の変化が樹木の生長と関係ない変動を示すことに気がつき、樹木近傍で測定した金属導体棒の接地抵抗と比較したところ同様な変化を示すことを見出した。金属導体棒の接地抵抗は、棒状導体の地面に打ち込んだ深さと棒状導体の直径および大地の比抵抗によって定まる。これら３つの定数のうち測定環境によって変動するのは比抵抗である。つまり、地中の水分量が降雨などによって増えれば、電気伝導性が増し、比抵抗は小さくなるため、接地抵抗も変化するのである。ゆえに、大地の比抵抗を植物の接地抵抗と同時に測定し、大地比抵抗の値で植物の接地抵抗値に一種の補正を施せば、大地比抵抗に影響されることなく植物本来の根の大きさや発達状態の推移を知ることができるようになる。
【００１３】
一般に、金属電極の電気接地抵抗Ｒは次の関数で表されることが知られている。Ｒ＝ρ・ｆここで、ρは大地の比抵抗を示し、ｆは金属電極の地中における形態（形状と寸法）によって定まる定数である。上の式は電気伝導性をもつ植物の根に対しても成り立つから、植物の生えている場所における大地の比抵抗ρと根の形態によって定まるｆとの積によって植物の接地抵抗が決定される。よって、植物の接地抵抗と大地比抵抗がわかればこれら二つの値から形状と寸法に関する定数ｆを求めることができる。つまり、植物の根がどのように複雑な形態と寸法を有していてもそれらに関する情報は最終的にはｆというひとつの値に置き代えることができることを意味する。このｆこそまさにその植物の根の大きさや発達状態を表す指標と考えることができる。
【００１４】
上述の指標ｆの大小によって根の発達状態を推定することは可能であるが、この値が単純な物理量に換算できると根の発達状態を一層理解しやすい。一般に金属電極の接地抵抗はそれと等価な半球状電極に変換して考えることが多い。すなわち、半球状電極の半径ｒを変えればその接地抵抗も変化するので、任意の接地抵抗はそれと等しい値をもつ半球状電極の半径に換算して考えるのである。この半径ｒを等価半径とよぶが、ｆが分かっていると等価半径ｒを求めることができ、その値はｒ＝１/(2πｆ)である。この変換は植物の根に対しても成り立つので、結局根はいかに複雑な形状と寸法を有しており、かついかなる接地抵抗値を有していても、それと同じ接地抵抗値をもつ半球状電極の半径ｒに換算して考えることができる。このように、ｆが具体的な長さｒに変換して与えられれば、この値の大小によって根の大きさや発達度合いを評価するのに好都合である。
【００１５】
等価半径の考え方は半球状電極の他に、円板状電極の半径に適用することも可能で、この場合は、ｒ＝１/（４ｆ）で表される。さらに、半径Ｌ長さＤの棒状電極に適用することもでき、適当な半径をもつ金属棒を接地したときに、どのくらいの深さまで埋め込めば測定対象と同じ接地抵抗値が得られるかが分かり、これは根の大きさを地中の深さ方向の値に換算することになる。棒状電極に換算した長さＤ（Ｄを等価長とよぶことにする）は、 2πｆＤ＝ln（２Ｄ／Ｌ）を解くことによって得られる。半球状電極の場合の等価半径は、根が根元から地中に放射状に伸びている場合を想定することができるのに対し、円板状電極の場合の等価半径は、根が地表に沿って地下に平面的に伸びている場合を想定できる。
【００１６】
図１は植物として樹木１０を対象とした場合を例にとり、樹木１０の接地抵抗を上述の等価半径ｒおよび等価長Ｄを算出するために必要な樹木の接地抵抗と大地１２の比抵抗を同時に測定する回路を示したものである。
図に示すように、大地１２に根ざした樹木１０の幹の地表から離れた部位に主電極Ｔを取り付ける。樹木１０から十分離れた大地１２に補助電極Ｃを設置する。樹木１０の幹の主電極Ｔより下方の地表付近に電極Ｅを取り付ける。樹木１０と補助電極Ｃとの間の大地１２に電極Ｐを取り付ける。
なお、電極Ｐは、電極Ｅ、Ｃ間の電圧分布において平坦な部分に設置する。補助電極Ｃの設置位置を測定樹木から５〜６ｍ以上離す（測定樹木が太い場合にはもっと離す）と、図１の下部に示すように、電極Ｅ、Ｃ間の地表の電圧分布には平坦な部分が生じるので、電極Ｐをこの平坦部の中央に設置するとよい。
【００１７】
対象樹木１０の根の接地抵抗ＲRを求めるためには、電源１８より電極Ｔ、Ｃ間に電圧を印加し、測定回路に流れる電流Ｉと対象樹木の地表レベルに取り付けた電極Ｅと補助電極Ｐの間の電位差ＶEPを測定し、ＶEPをＩで割ることによって求める。一方、大地比抵抗は電極Ｃの接地抵抗値から求める。測定回路に流れる電流Ｉと対象電極Ｃと補助電極Ｐの間の電位差ＶPCを測定すれば、電極Ｃの接地抵抗はＶPC/Ｉとして求まる。電極Ｃには寸法が既知の棒状電極を用いるので、その半径aと、地中に打ち込んだ深さｂ（ｂ≫ａ）および上で求めた接地抵抗ＲCから公式、ρ＝２πｂＲC／ｌｎ(２ｂ/a) により大地の比抵抗を求めることができる。この測定は比抵抗測定のために新たな電極配置をとる必要がなく、樹木の接地抵抗測定のための電極配置をそのまま利用するところに特徴がある。
【００１８】
前記のように、ＲR＝ρｆであり、植物の根と同じ接地抵抗をもつ半球状電極の半径をｒとしたとき、ｒ＝１／（２πｆ）であるから、植物の根の等価半径ｒを、式、ｒ＝ρ／（２πＲR）で求めることができる。
また、植物の根と同じ接地抵抗をもつ円板状電極の半径をｒとしたとき、ｒ＝１／（４ｆ）であるから、植物の根の等価半径ｒを、式、ｒ＝ρ／（４ＲR）で求めることができる。
さらに、植物の根と同じ接地抵抗をもつ棒状電極（半径Ｌ、長さＤ、Ｌ≪Ｄ）の半径Ｌを適当に定めたとき、植物の根の等価長さＤを、式、２πＲRＤ＝ρｌｎ(２Ｄ/Ｌ)で求めることができる。
【００１９】
上述したように植物の根の等価半径ｒおよび等価長Ｄを求めるには、大地比抵抗ρの値を知る必要があり、図１に示す補助電極Ｃの接地抵抗値と電極寸法から算出した値を利用する。しかし、大地比抵抗値は直接知る必要はなく等価半径および等価長を算出する過程で消去できるので、最終的には植物の根の接地抵抗と補助電極Ｃの接地抵抗および物理的寸法が分かればよい。すなわち、植物の根の接地抵抗はＲR＝ρ・ｆR と表され、補助電極Ｃの接地抵抗はＲC＝ρ・ｆC と表される。これら二つの式から大地比抵抗ρを消去すると、根の形状および寸法に関する定数はｆR＝ＲRｆC／ＲCとなる。一方、半球状電極の形状および寸法に関する定数は先述したように１／（２πｒ）である。これをｆRとすると、等価半径はｒ＝ＲC／（２πＲRｆC）と求まる。ｆC は補助電極Ｃ（棒状電極）の形状と寸法に関する関数で、半径をａ、地中部の長さをｂとするとｆC＝ｌｎ(２ｂ/a)／（２πｂ）であり、これを先の式に代入すると、最終的に植物の根の等価半径はｒ＝ｂＲC／（ＲRｌｎ(2ｂ/a)）と求まる。この式から分かることは、対象植物の接地抵抗ＲRおよび棒状の補助電極Ｃの接地抵抗ＲCと寸法a、bが分かれば、等価半径ｒを算出でき、大地比抵抗値は直接必要としないことを示している。
【００２０】
上と同様にして円板状電極の等価半径ｒを求めると、ｒ＝πｂＲC／（2ＲRｌｎ(２ｂ/a)）で与えられる。
棒状電極の場合については、適当な大きさにとった半径Ｌの電極が地中にどのくらいの深さまで入っているかその長さＤを等価長とするので、ｆR＝ln（２Ｄ／Ｌ）／２πＤである。これと補助電極Ｃの定数ｆCから、ln（２Ｄ／Ｌ）／Ｄ＝ＲRｌｎ(２ｂ/a) ／ｂＲCの関係が得られ、等価長Ｄはこの式を解くことによって与えられる。上の結果からわかるように円板状電極、棒状電極においても等価半径、等価長を求めるのに大地比抵抗値は直接必要としないことを示している
【００２１】
以上によって得た等価半径、等価長を、いろいろな植物／樹木についてそれぞれの根の態様に応じて適用しその値の大小から、個体間の根の大きさの違い、および経時変化から根の発達状態等の比較を行う。
【００２２】
なお、電極Ｔ、Ｅは、特開平１１−３３２３７７号に示したものと同様のものを使用できる。
すなわち、電極Ｅは、１本の針状もしくは釘状の電極を用い、地表面付近の幹の外周に幹の中心に向けて差し込んで取り付ける。
また、電極Ｔは、針状もしくは釘状のものを用いる場合には複数本使用し、幹の外周上、ほぼ同一の水平面上であって、等間隔になるように、中心に向けて差し込むようにするとよい。
【００２３】
あるいは、電極Ｅおよび／または電極Ｔに、導電性帯状体を用い、樹木の幹の外周面に水平に巻きつけて取り付け、樹木とは樹木の外周面と導電性帯状体との間に形成される容量（キャパシタンス）をもって電気的に接続し、電極Ｔから電流を幹に供給したり、また電極Ｅにおいて電圧を測定するようにしてもよい。なお、この場合、実際には、幹の外周面に電気的絶縁性を有する材料を巻き、その上から導電性帯状体を巻きつけるようにして、接触抵抗を無くす構成とする。導電性帯状体としては、アルミ箔、可撓性を有するスチールベルト等の導電性金属ベルト、銅網、導電性繊維フェルト等が採用し得る。
【００２４】
【発明の効果】
本発明によれば、植物の根の接地抵抗から大地の比抵抗の影響を除いて、根本来の形態的特徴を半球状電極または円板状電極の等価半径で、さらに棒状電極の等価長で数値的に表すことができるため、根の大きさや発達状態を大地の乾湿状態と関係なく評価することができる。しかして、植物の根の大きさや成長状態を大地の比抵抗に左右されることなく評価することが可能となった。
【図面の簡単な説明】
【図１】本発明に係る大地比抵抗、等価半径および等価長を求めるための測定回路である。
【符号の説明】
１０ 樹木
１２ 大地
Ｔ、Ｅ、Ｐ、Ｃ 電極
１８ 電源[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for evaluating plant roots.
[0002]
[Prior art]
Plant roots play an important role in plant growth because they grow in the ground by absorbing water and nutrients from the roots. From a long time ago, as a method for judging the quality of the growth state of a plant, there is a method of judging based on the tension of the roots. In other words, when the roots are stretched far from the trunk of the plant, the root growth is good, so the growth of the plant is good. Conversely, when the root tension is not good, the growth of the plant is poor. It is judged that it is.
However, since the roots of the food are in the ground, it is impossible to judge the tension from the ground, and if part of the roots happen to be exposed on the ground surface, there is a gap between the exposed roots and the trunk. You can judge how far the root is from the trunk of the plant from the distance, but if not, you can not confirm the root of the root without actually digging the soil . As described above, there is a problem that the degree of root tension cannot be easily confirmed.
[0003]
Therefore, the inventor found that the root of the plant is in the ground and the surface is in contact with the soil, so when considering the electrical resistance between the root of the plant and the ground, When the tension is good, the contact area between the root and the soil increases, so the electrical resistance between the root of the plant and the ground is smaller than when the root tension is bad. A method for determining the growth status of a plant by measuring resistance (ground resistance) was proposed (Japanese Patent Laid-Open No. 11-332377).
[0004]
[Problems to be solved by the invention]
However, since the ground resistance value is affected by the specific resistance of the ground, it is possible to compare the size and development of plant roots at the same place of the ground specific resistance. Developmental status cannot be accurately assessed. Since the resistivity of the earth varies greatly depending on the degree of dryness and wetness of the earth, even if it is the same place, it will have a different value after it rains and after clear weather. Therefore, since the ground resistance value of the root increases or decreases depending on the value of the earth resistivity on the day of measurement, it is difficult to accurately evaluate the size and development state of each root over time. .
[0005]
[Problems to be solved by the invention]
Therefore, the present invention is intended to solve the above inconvenience, and provides a method capable of knowing the original size of the root and the time transition of the developmental state regardless of the change in the resistivity of the earth. Specifically, it aims to provide an electrode arrangement for simultaneously measuring the ground resistance and ground resistivity of the root in the same circuit, and to provide a method capable of numerically evaluating the size and development of the root. .
[0006]
[Means for Solving the Problems]
The plant root evaluation method according to the present invention is a method in which a main electrode T is attached to a site away from the surface of a plant stem or trunk rooted in the ground, and an auxiliary electrode C is installed on the ground sufficiently away from the plant, An electrode E is attached near the ground surface below the main electrode T of the stem or stem of the plant, and the potential distribution of the ground between the plant and the auxiliary electrode C is obtained, and the electrode P is formed in a region where the potential distribution becomes flat. And a measurement current flowing through the ground through the plant between the main electrode T and the auxiliary electrode C, and a voltage value V EP between the electrode E and the electrode P is measured and measured. The voltage value V EP is divided by the current value I of the measurement current to obtain a ground resistance value R R between the ground and the plant root, and the electrode P when the measurement current is passed the auxiliary electrode to measure the voltage value V PC between C, and measured the voltage value V PC of the measuring current Divided by current values I seek ground resistance R C of the auxiliary electrode C, and the radius of the auxiliary electrode C a, when the embedding depth was b (b»a), earth resistivity [rho, wherein ρ = 2πbR C / ln (2b / a), where r is the radius of a hemispherical electrode having the same ground resistance as the plant root, and the equivalent radius r of the plant root is expressed by the equation: r = ρ / ( 2πR R ).
[0007]
Moreover, in the plant root evaluation method according to the present invention, the main electrode T is attached to a part of the plant stem or stem that is rooted in the ground, and the auxiliary electrode C is installed on the ground sufficiently away from the plant, An electrode E is attached near the ground surface below the main electrode T of the stem or stem of the plant, and the potential distribution of the ground between the plant and the auxiliary electrode C is obtained, and an electrode is formed in a region where the potential distribution is flat. P is installed, a measurement current flowing through the ground through the plant is passed between the main electrode T and the auxiliary electrode C, and a voltage value V EP between the electrode E and the electrode P is measured, The measured voltage value VEP is divided by the current value I of the current for measurement to obtain a ground resistance value R R between the ground and the plant root, and the electrode P when the current for measurement is passed. the measured voltage value V PC between the auxiliary electrode C and, for the measurement of measured the voltage value V PC Divided by the current value I of the flow obtains a grounding resistance value R C of the auxiliary electrode C, and the radius of the auxiliary electrode C a, when the embedding depth was b (b»a), earth resistivity [rho, Ρ = 2πbR C / ln (2b / a), where the radius of a disk-like electrode having the same ground resistance as that of the plant root is r, the equivalent radius r of the plant root is expressed by the equation r = It is characterized by obtaining by ρ / (4R R ).
[0008]
Furthermore, in the plant root evaluation method according to the present invention, the main electrode T is attached to a site away from the ground surface of the stem and trunk of the plant rooted in the ground, and the auxiliary electrode C is installed on the ground sufficiently away from the plant, An electrode E is attached near the ground surface below the main electrode T of the stem or stem of the plant, and the potential distribution of the ground between the plant and the auxiliary electrode C is obtained, and an electrode is formed in a region where the potential distribution is flat. P is installed, a measurement current flowing through the ground through the plant is passed between the main electrode T and the auxiliary electrode C, and a voltage value V EP between the electrode E and the electrode P is measured, The measured voltage value VEP is divided by the current value I of the current for measurement to obtain a ground resistance value R R between the ground and the plant root, and the electrode P when the current for measurement is passed. the measured voltage value V PC between the auxiliary electrode C and the measured measured the voltage value V PC Divided by the current value I of the current seeking the ground resistance R C of the auxiliary electrode C, and the radius of the auxiliary electrode C a, when the embedding depth and is b, earth resistivity [rho, wherein, ρ = 2πbR When the radius L of a rod-like electrode (radius L, length D, L << D) having the same grounding resistance as the plant root is appropriately determined, the equivalent length of the plant root is obtained by C / ln (2b / a) The feature D is obtained by the formula 2πR R D = ρln (2D / L).
[0009]
Moreover, in the plant root evaluation method according to the present invention, the main electrode T is attached to a part of the plant stem or stem that is rooted in the ground, and the auxiliary electrode C is installed on the ground sufficiently away from the plant, An electrode E is attached near the ground surface below the main electrode T of the stem or stem of the plant, and the potential distribution of the ground between the plant and the auxiliary electrode C is obtained, and an electrode is formed in a region where the potential distribution is flat. P is installed, a measurement current flowing through the ground through the plant is passed between the main electrode T and the auxiliary electrode C, and a voltage value V EP between the electrode E and the electrode P is measured, The measured voltage value VEP is divided by the current value I of the current for measurement to obtain a ground resistance value R R between the ground and the plant root, and the electrode P when the current for measurement is passed. the measured voltage value V PC between the auxiliary electrode C and, for the measurement of measured the voltage value V PC Divided by the current value I of the flow obtains a grounding resistance value R C of the auxiliary electrode C, wherein the radius of the auxiliary electrode C a, the embedding depth b (b»a), hemisphere having the same ground resistance as the roots of the plant When the radius of the electrode is r, the equivalent radius r of the root of the plant is obtained by the equation: r = bR C / (R R ln (2b / a)).
[0010]
Furthermore, in the plant root evaluation method according to the present invention, the main electrode T is attached to a part of the plant that is rooted in the ground, away from the ground surface of the stem or trunk, and the auxiliary electrode C is installed in the ground sufficiently away from the plant. The electrode E is attached near the ground surface below the main electrode T of the plant stem and trunk, and the potential distribution of the ground between the plant and the auxiliary electrode C is obtained to obtain a region where the potential distribution becomes flat. An electrode P is installed, a measurement current flowing through the ground through the plant is passed between the main electrode T and the auxiliary electrode C, and a voltage value V EP between the electrode E and the electrode P is measured. The measured voltage value VEP is divided by the current value I of the measurement current to obtain a ground resistance value R R between the ground and the plant root, and the electrode when the measurement current is passed measuring the voltage value V PC between P and the auxiliary electrode C, wherein the measured the voltage value V PC Divided by the current value I calculated ground resistance R C of the auxiliary electrode C of the titration, the current, the radius of the auxiliary electrode C a, buried depth b, disc-shaped electrodes having the same ground resistance as the roots of the plant Where r is the radius, the equivalent radius r of the root of the plant is obtained by the equation: r = πbR c / (2R R ln (2b / a)).
[0011]
Furthermore, in the plant root evaluation method according to the present invention, the main electrode T is attached to a site away from the ground surface of the stem and trunk of the plant rooted in the ground, and the auxiliary electrode C is installed on the ground sufficiently away from the plant, An electrode E is attached near the ground surface below the main electrode T of the stem or stem of the plant, and the potential distribution of the ground between the plant and the auxiliary electrode C is obtained, and an electrode is formed in a region where the potential distribution is flat. P is installed, a measurement current flowing through the ground through the plant is passed between the main electrode T and the auxiliary electrode C, and a voltage value V EP between the electrode E and the electrode P is measured, The measured voltage value VEP is divided by the current value I of the current for measurement to obtain a ground resistance value R R between the ground and the plant root, and the electrode P when the current for measurement is passed. the measured voltage value V PC between the auxiliary electrode C and the measured measured the voltage value V PC Divided by the current value I of the current seeking the ground resistance R C of the auxiliary electrode C, wherein the radius of the auxiliary electrode C a, the embedding depth b (b»a), rod-shaped with the same ground resistance as the roots of the plant When the radius L of the electrode (radius L, length D, L << D) is appropriately determined, the equivalent length D of the root of the plant is expressed by the formula ln (2D / L) / D = R R ln (2b / a) It is obtained from / (bR C ).
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
The inventor measured the electrical resistance between the tree and the ground in the form of ground resistance, and as a result of measuring the change in the ground resistance of a single tree day by day, the change in the value shows a variation not related to the growth of the tree. We noticed that we found similar changes when compared to the ground resistance of metal bars measured near trees. The ground resistance of the metal conductor rod is determined by the depth of the rod conductor driven into the ground, the diameter of the rod conductor, and the specific resistance of the ground. Of these three constants, the specific resistance varies depending on the measurement environment. In other words, if the amount of water in the ground increases due to rain or the like, the electrical conductivity increases and the specific resistance decreases, so the grounding resistance also changes. Therefore, if the specific resistance of the ground is measured simultaneously with the ground resistance of the plant, and if a kind of correction is made to the ground resistance value of the plant by the value of the ground specific resistance, the size of the original root of the plant is not affected by the ground specific resistance. It becomes possible to know the transition of the sheath development state.
[0013]
In general, it is known that the electrical grounding resistance R of a metal electrode is expressed by the following function. R = ρ · f where ρ represents the specific resistance of the ground, and f is a constant determined by the shape (shape and size) of the metal electrode in the ground. Since the above equation holds for the root of a plant having electrical conductivity, the ground resistance of the plant is determined by the product of the specific resistance ρ of the ground where the plant grows and f determined by the form of the root. . Therefore, if the ground resistance and ground resistivity of the plant are known, the constant f regarding the shape and size can be obtained from these two values. That is, no matter how complex the plant roots have dimensions and dimensions, the information about them can ultimately be replaced by a single value of f. This f can be considered as an index that represents the size and developmental state of the root of the plant.
[0014]
Although it is possible to estimate the state of root development based on the magnitude of the above-described index f, it is easier to understand the state of root development if this value can be converted into a simple physical quantity. In general, the ground resistance of a metal electrode is often considered by converting it to an equivalent hemispherical electrode. That is, if the radius r of the hemispherical electrode is changed, the grounding resistance also changes. Therefore, an arbitrary grounding resistance is considered in terms of the radius of the hemispherical electrode having the same value. This radius r is called an equivalent radius. If f is known, the equivalent radius r can be obtained, and its value is r = 1 / (2πf). This transformation is also true for the roots of plants, so eventually the hemispherical electrodes have the same ground resistance value, regardless of how complex the shape and dimensions of the roots and any ground resistance value. It can be considered in terms of the radius r. Thus, if f is converted into a specific length r and given, it is convenient to evaluate the root size and the degree of development based on the magnitude of this value.
[0015]
The concept of the equivalent radius can be applied to the radius of the disc-shaped electrode in addition to the hemispherical electrode, and in this case, r = 1 / (4f). Furthermore, it can be applied to a rod-shaped electrode having a radius L and a length D, and when a metal rod having an appropriate radius is grounded, it can be understood how much depth can be embedded to obtain the same grounding resistance value as the object to be measured, This translates the size of the root into a value in the depth direction of the ground. The length D converted into a rod-like electrode (D is called an equivalent length) can be obtained by solving for 2πfD = ln (2D / L). The equivalent radius in the case of a hemispherical electrode can be assumed when the root extends radially from the root into the ground, whereas the equivalent radius in the case of a disk-shaped electrode is that the root is along the ground surface. It can be assumed that it extends flat underground.
[0016]
FIG. 1 shows an example in which a
As shown in the figure, the main electrode T is attached to a part away from the ground surface of the trunk of the
The electrode P is placed on a flat portion in the voltage distribution between the electrodes E and C. When the installation position of the auxiliary electrode C is separated from the measurement tree by 5 to 6 m or more (more away if the measurement tree is thick), the ground voltage distribution between the electrodes E and C is flat as shown in the lower part of FIG. Therefore, the electrode P is preferably installed at the center of the flat portion.
[0017]
To determine the grounding resistance R R of the root of the
[0018]
As described above, when R R = ρf and the radius of the hemispherical electrode having the same ground resistance as that of the plant root is r, r = 1 / (2πf), so that the equivalent radius r of the plant root Can be obtained by the equation, r = ρ / (2πR R ).
Since r = 1 / (4f) where r is the radius of the disk electrode having the same ground resistance as the plant root, the equivalent radius r of the plant root is expressed by the equation: r = ρ / ( 4R R ).
Furthermore, when the radius L of the rod-shaped electrode (radius L, length D, L << D) having the same ground resistance as that of the plant root is appropriately determined, the equivalent length D of the plant root is expressed by the formula 2πR R D = Ρln (2D / L).
[0019]
As described above, in order to obtain the equivalent radius r and equivalent length D of the root of the plant, it is necessary to know the value of the ground resistivity ρ, which is a value calculated from the ground resistance value and electrode dimensions of the auxiliary electrode C shown in FIG. Is used. However, it is not necessary to know the ground specific resistance value directly, and it can be deleted in the process of calculating the equivalent radius and equivalent length. Therefore, if the ground resistance of the plant root, the ground resistance of the auxiliary electrode C and the physical dimensions are finally known, Good. That is, the ground resistance of the plant root is expressed as R R = ρ · f R, and the ground resistance of the auxiliary electrode C is expressed as R C = ρ · f C. If the ground resistivity ρ is eliminated from these two equations, the constants related to the shape and dimensions of the root are f R = R R f C / R C. On the other hand, the constant related to the shape and size of the hemispherical electrode is 1 / (2πr) as described above. Assuming that this is f R , the equivalent radius is obtained as r = R C / (2πR R f C ). f C is a function related to the shape and dimensions of the auxiliary electrode C (rod-shaped electrode). When the radius is a and the length of the underground portion is b, f C = ln (2b / a) / (2πb), Substituting into this equation, the equivalent radius of the root of the plant is finally obtained as r = bR C / (R R ln (2b / a)). It can be understood from this equation that if the ground resistance R R of the target plant and the ground resistance R C of the rod-shaped auxiliary electrode C and the dimensions a and b are known, the equivalent radius r can be calculated, and the ground specific resistance value is not directly required. It is shown that.
[0020]
When the equivalent radius r of the disk-like electrode is obtained in the same manner as above, it is given by r = πbR C / (2R R ln (2b / a)).
In the case of a rod-shaped electrode, since the length D is an equivalent length to which depth an electrode of an appropriate radius L is placed in the ground, f R = ln (2D / L) / 2πD. From constant f C of this auxiliary electrode C, ln (2D / L) / D = R R ln (2b / a) / bR C relationship is obtained, the equivalent length D is given by solving the equation. As can be seen from the above results, it is shown that the ground specific resistance value is not directly required for obtaining the equivalent radius and the equivalent length even in the case of the disk-like electrode and the rod-like electrode.
Equivalent radii and equivalent lengths obtained above are applied to various plants / trees according to the mode of their roots, and the development of the roots based on the difference in the size of the roots between individuals and the changes over time. Compare the status.
[0022]
The electrodes T and E can be the same as those disclosed in JP-A-11-332377.
That is, the electrode E uses one needle-like or nail-like electrode, and is attached by being inserted toward the outer periphery of the trunk near the ground surface toward the center of the trunk.
In addition, when using a needle-like or nail-like one, use a plurality of electrodes T, and insert them toward the center so that they are on the outer circumference of the trunk, on substantially the same horizontal plane, and at equal intervals. It is good to.
[0023]
Alternatively, a conductive strip is used as the electrode E and / or the electrode T, and is wrapped around and attached to the outer peripheral surface of the trunk of the tree, and the tree is formed between the outer peripheral surface of the tree and the conductive strip. It is also possible to electrically connect with a certain capacitance (capacitance), supply a current from the electrode T to the trunk, or measure the voltage at the electrode E. In this case, in practice, a material having electrical insulating properties is wound around the outer peripheral surface of the trunk, and a conductive belt-like body is wound thereon to eliminate contact resistance. As the conductive strip, an aluminum foil, a conductive metal belt such as a flexible steel belt, a copper net, a conductive fiber felt, or the like can be used.
[0024]
【The invention's effect】
According to the present invention, except for the influence of the specific resistance of the ground from the ground resistance of the root of the plant, the original morphological characteristics of the root are the equivalent radius of the hemispherical electrode or the disc-like electrode, and the equivalent length of the rod-like electrode. Since it can be expressed numerically, the size and development of the roots can be evaluated regardless of the wet and dry conditions of the earth. Therefore, it became possible to evaluate the size and growth state of plant roots without being influenced by the resistivity of the earth.
[Brief description of the drawings]
FIG. 1 is a measurement circuit for obtaining a ground resistivity, an equivalent radius, and an equivalent length according to the present invention.
[Explanation of symbols]
10
Claims (6)
前記植物から十分離れた大地に補助電極Ｃを設置し、
前記植物の茎や幹の前記主電極Ｔより下方の地表付近に電極Ｅを取り付け、
前記植物と前記補助電極Ｃとの間の大地の電位分布を求めて該電位分布が平坦となる領域に電極Ｐを設置し、
前記主電極Ｔと前記補助電極Ｃとの間に植物を通って大地を流れる測定用電流を流し、
前記電極Ｅと前記電極Ｐとの間の電圧値ＶEPを測定し、
測定した該電圧値ＶEPを前記測定用電流の電流値Ｉで割って大地と前記植物の根との間の接地抵抗値ＲRを求め、
前記測定用電流を流した際の、前記電極Ｐと前記補助電極Ｃとの間の電圧値ＶPCを測定し、
測定した該電圧値ＶPCを前記測定用電流の電流値Ｉで割って補助電極Ｃの接地抵抗値ＲCを求め、
前記補助電極Ｃの半径をａ、埋めこみ深さをｂ（ｂ≫ａ）としたとき、大地の比抵抗ρを、
式、ρ＝２πｂＲC／ｌｎ(２ｂ/a)で求め、
植物の根と同じ接地抵抗をもつ半球状電極の半径をｒとしたとき、植物の根の等価半径ｒを、式、ｒ＝ρ／（２πＲR）で求めることを特徴とする植物の根の評価方法。Attach the main electrode T to the part of the plant that is rooted in the earth
Auxiliary electrode C is installed on the ground sufficiently away from the plant,
An electrode E is attached near the ground surface below the main electrode T of the plant stem or stem,
An electrode P is installed in a region where the potential distribution becomes flat by obtaining the potential distribution of the ground between the plant and the auxiliary electrode C;
A current for measurement flowing through the ground through the plant between the main electrode T and the auxiliary electrode C;
A voltage value V EP between the electrode E and the electrode P is measured;
Dividing the measured voltage value V EP by the current value I of the current for measurement to obtain a ground resistance value R R between the ground and the root of the plant,
Measuring the voltage value V PC between the electrode P and the auxiliary electrode C when the measurement current is passed;
Dividing the measured the voltage value V PC at a current value I of the current for measurement seeking ground resistance R C of the auxiliary electrode C,
When the radius of the auxiliary electrode C is a and the embedding depth is b (b >> a), the resistivity ρ of the ground is
The equation, ρ = 2πbR C / ln (2b / a),
When the radius of a hemispherical electrode having the same ground resistance as that of the plant root is r, the equivalent radius r of the plant root is obtained by the equation: r = ρ / (2πR R ) Evaluation methods.
前記植物から十分離れた大地に補助電極Ｃを設置し、
前記植物の茎や幹の前記主電極Ｔより下方の地表付近に電極Ｅを取り付け、
前記植物と前記補助電極Ｃとの間の大地の電位分布を求めて該電位分布が平坦となる領域に電極Ｐを設置し、
前記主電極Ｔと前記補助電極Ｃとの間に植物を通って大地を流れる測定用電流を流し、
前記電極Ｅと前記電極Ｐとの間の電圧値ＶEPを測定し、
測定した該電圧値ＶEPを前記測定用電流の電流値Ｉで割って大地と前記植物の根との間の接地抵抗値ＲRを求め、
前記測定用電流を流した際の、前記電極Ｐと前記補助電極Ｃとの間の電圧値ＶPCを測定し、
測定した該電圧値ＶPCを前記測定用電流の電流値Ｉで割って補助電極Ｃの接地抵抗値ＲCを求め、
前記補助電極Ｃの半径をａ、埋めこみ深さをｂ（ｂ≫ａ）としたとき、大地の比抵抗ρを、
式、ρ＝２πｂＲC／ｌｎ(２ｂ/a)で求め、
植物の根と同じ接地抵抗をもつ円板状電極の半径をｒとしたとき、植物の根の等価半径ｒを、式、ｒ＝ρ／（４ＲR）で求めることを特徴とする植物の根の評価方法。Attach the main electrode T to the part of the plant that is rooted in the earth
Auxiliary electrode C is installed on the ground sufficiently away from the plant,
An electrode E is attached near the ground surface below the main electrode T of the plant stem or stem,
An electrode P is installed in a region where the potential distribution becomes flat by obtaining the potential distribution of the ground between the plant and the auxiliary electrode C;
A current for measurement flowing through the ground through the plant between the main electrode T and the auxiliary electrode C;
A voltage value V EP between the electrode E and the electrode P is measured;
The measured voltage value V EP is divided by the current value I of the current for measurement to obtain a ground resistance value R R between the ground and the root of the plant,
Measuring the voltage value V PC between the electrode P and the auxiliary electrode C when the measurement current is passed;
Dividing the measured the voltage value V PC at a current value I of the current for measurement seeking ground resistance R C of the auxiliary electrode C,
When the radius of the auxiliary electrode C is a and the embedding depth is b (b >> a), the resistivity ρ of the ground is
The equation, ρ = 2πbR C / ln (2b / a),
The root of the plant is characterized in that the equivalent radius r of the root of the plant is obtained by the equation: r = ρ / (4R R ), where r is the radius of the disk electrode having the same ground resistance as the root of the plant. Evaluation method.
前記植物から十分離れた大地に補助電極Ｃを設置し、
前記植物の茎や幹の前記主電極Ｔより下方の地表付近に電極Ｅを取り付け、
前記植物と前記補助電極Ｃとの間の大地の電位分布を求めて該電位分布が平坦となる領域に電極Ｐを設置し、
前記主電極Ｔと前記補助電極Ｃとの間に植物を通って大地を流れる測定用電流を流し、
前記電極Ｅと前記電極Ｐとの間の電圧値ＶEPを測定し、
測定した該電圧値ＶEPを前記測定用電流の電流値Ｉで割って大地と前記植物の根との間の接地抵抗値ＲRを求め、
前記測定用電流を流した際の、前記電極Ｐと前記補助電極Ｃとの間の電圧値ＶPCを測定し、
測定した該電圧値ＶPCを前記測定用電流の電流値Ｉで割って補助電極Ｃの接地抵抗値ＲCを求め、
前記補助電極Ｃの半径をａ、埋めこみ深さをｂ（ｂ≫ａ）としたとき、大地の比抵抗ρを、
式、ρ＝２πｂＲC／ｌｎ(２ｂ/a)で求め、
植物の根と同じ接地抵抗をもつ棒状電極（半径Ｌ、長さＤ、Ｌ≪Ｄ）の半径Ｌを適当に定めたとき、植物の根の等価長さＤを、式、２πＲRＤ＝ρｌｎ(２Ｄ/Ｌ)で求めることを特徴とする植物の根の評価方法。Attach the main electrode T to the part of the plant that is rooted in the earth
Auxiliary electrode C is installed on the ground sufficiently away from the plant,
An electrode E is attached near the ground surface below the main electrode T of the plant stem or stem,
An electrode P is installed in a region where the potential distribution becomes flat by obtaining the potential distribution of the ground between the plant and the auxiliary electrode C;
A current for measurement flowing through the ground through the plant between the main electrode T and the auxiliary electrode C;
A voltage value V EP between the electrode E and the electrode P is measured;
The measured voltage value V EP is divided by the current value I of the current for measurement to obtain a ground resistance value R R between the ground and the root of the plant,
Measuring the voltage value V PC between the electrode P and the auxiliary electrode C when the measurement current is passed;
Dividing the measured the voltage value V PC at a current value I of the current for measurement seeking ground resistance R C of the auxiliary electrode C,
When the radius of the auxiliary electrode C is a and the embedding depth is b (b >> a), the resistivity ρ of the ground is
The equation, ρ = 2πbR C / ln (2b / a),
When the radius L of the rod-shaped electrode (radius L, length D, L << D) having the same ground resistance as that of the plant root is appropriately determined, the equivalent length D of the plant root is expressed by the formula 2πR R D = ρln A method for evaluating plant roots, characterized in that it is determined by (2D / L).
前記植物から十分離れた大地に補助電極Ｃを設置し、
前記植物の茎や幹の前記主電極Ｔより下方の地表付近に電極Ｅを取り付け、
前記植物と前記補助電極Ｃとの間の大地の電位分布を求めて該電位分布が平坦となる領域に電極Ｐを設置し、
前記主電極Ｔと前記補助電極Ｃとの間に植物を通って大地を流れる測定用電流を流し、
前記電極Ｅと前記電極Ｐとの間の電圧値ＶEPを測定し、
測定した該電圧値ＶEPを前記測定用電流の電流値Ｉで割って大地と前記植物の根との間の接地抵抗値ＲRを求め、
前記測定用電流を流した際の、前記電極Ｐと前記補助電極Ｃとの間の電圧値ＶPCを測定し、
測定した該電圧値ＶPCを前記測定用電流の電流値Ｉで割って補助電極Ｃの接地抵抗値ＲCを求め、
前記補助電極Ｃの半径をａ、埋めこみ深さをｂ（ｂ≫ａ）、植物の根と同じ接地抵抗をもつ半球状電極の半径をｒとしたとき、植物の根の等価半径ｒを、式、ｒ＝ｂＲC／（ＲRｌｎ(2ｂ/a)）で求めることを特徴とする植物の根の評価方法。Attach the main electrode T to the part of the plant that is rooted in the earth
Auxiliary electrode C is installed on the ground sufficiently away from the plant,
An electrode E is attached near the ground surface below the main electrode T of the plant stem or stem,
An electrode P is installed in a region where the potential distribution becomes flat by obtaining the potential distribution of the ground between the plant and the auxiliary electrode C;
A current for measurement flowing through the ground through the plant between the main electrode T and the auxiliary electrode C;
A voltage value V EP between the electrode E and the electrode P is measured;
The measured voltage value V EP is divided by the current value I of the current for measurement to obtain a ground resistance value R R between the ground and the root of the plant,
Measuring the voltage value V PC between the electrode P and the auxiliary electrode C when the measurement current is passed;
Dividing the measured the voltage value V PC at a current value I of the current for measurement seeking ground resistance R C of the auxiliary electrode C,
When the radius of the auxiliary electrode C is a, the embedding depth is b (b >> a), and the radius of the hemispherical electrode having the same ground resistance as the root of the plant is r, the equivalent radius r of the root of the plant is expressed by the formula , R = bR C / (R R In (2b / a))
前記植物から十分離れた大地に補助電極Ｃを設置し、
前記植物の茎や幹の前記主電極Ｔより下方の地表付近に電極Ｅを取り付け、
前記植物と前記補助電極Ｃとの間の大地の電位分布を求めて該電位分布が平坦となる領域に電極Ｐを設置し、
前記主電極Ｔと前記補助電極Ｃとの間に植物を通って大地を流れる測定用電流を流し、
前記電極Ｅと前記電極Ｐとの間の電圧値ＶEPを測定し、
測定した該電圧値ＶEPを前記測定用電流の電流値Ｉで割って大地と前記植物の根との間の接地抵抗値ＲRを求め、
前記測定用電流を流した際の、前記電極Ｐと前記補助電極Ｃとの間の電圧値ＶPCを測定し、
測定した該電圧値ＶPCを前記測定用電流の電流値Ｉで割って補助電極Ｃの接地抵抗値ＲCを求め、
前記補助電極Ｃの半径をａ、埋めこみ深さをｂ（ｂ≫ａ）、植物の根と同じ接地抵抗をもつ円板状電極の半径をｒとしたとき、植物の根の等価半径ｒを、式、ｒ＝πｂＲC／（2ＲRｌｎ(２ｂ/a)）で求めることを特徴とする植物の根の評価方法。Attach the main electrode T to the part of the plant that is rooted in the earth
Auxiliary electrode C is installed on the ground sufficiently away from the plant,
An electrode E is attached near the ground surface below the main electrode T of the plant stem or stem,
An electrode P is installed in a region where the potential distribution becomes flat by obtaining the potential distribution of the ground between the plant and the auxiliary electrode C;
A current for measurement flowing through the ground through the plant between the main electrode T and the auxiliary electrode C;
A voltage value V EP between the electrode E and the electrode P is measured;
The measured voltage value V EP is divided by the current value I of the current for measurement to obtain a ground resistance value R R between the ground and the root of the plant,
Measuring the voltage value V PC between the electrode P and the auxiliary electrode C when the measurement current is passed;
Dividing the measured the voltage value V PC at a current value I of the current for measurement seeking ground resistance R C of the auxiliary electrode C,
When the radius of the auxiliary electrode C is a, the embedding depth is b (b >> a), and the radius of the disk electrode having the same ground resistance as the root of the plant is r, the equivalent radius r of the root of the plant is A method for evaluating a plant root, which is calculated by the formula: r = πbR C / (2R R ln (2b / a)).
前記植物から十分離れた大地に補助電極Ｃを設置し、
前記植物の茎や幹の前記主電極Ｔより下方の地表付近に電極Ｅを取り付け、
前記植物と前記補助電極Ｃとの間の大地の電位分布を求めて該電位分布が平坦となる領域に電極Ｐを設置し、
前記主電極Ｔと前記補助電極Ｃとの間に植物を通って大地を流れる測定用電流を流し、
前記電極Ｅと前記電極Ｐとの間の電圧値ＶEPを測定し、
測定した該電圧値ＶEPを前記測定用電流の電流値Ｉで割って大地と前記植物の根との間の接地抵抗値ＲRを求め、
前記測定用電流を流した際の、前記電極Ｐと前記補助電極Ｃとの間の電圧値ＶPCを測定し、
測定した該電圧値ＶPCを前記測定用電流の電流値Ｉで割って補助電極Ｃの接地抵抗値ＲCを求め、
前記補助電極Ｃの半径をａ、埋めこみ深さをｂ（ｂ≫ａ）、植物の根と同じ接地抵抗をもつ棒状電極（半径Ｌ、長さＤ、Ｌ≪Ｄ）の半径Ｌを適当に定めたとき、植物の根の等価長さＤを、式、ln（２Ｄ／Ｌ）／Ｄ＝ＲRｌｎ(２ｂ/a) ／（ｂＲC）から求めることを特徴とする植物の根の評価方法。Attach the main electrode T to the part of the plant that is rooted in the earth
Auxiliary electrode C is installed on the ground sufficiently away from the plant,
An electrode E is attached near the ground surface below the main electrode T of the plant stem or stem,
An electrode P is installed in a region where the potential distribution becomes flat by obtaining the potential distribution of the ground between the plant and the auxiliary electrode C;
A current for measurement flowing through the ground through the plant between the main electrode T and the auxiliary electrode C;
A voltage value V EP between the electrode E and the electrode P is measured;
The measured voltage value V EP is divided by the current value I of the current for measurement to obtain a ground resistance value R R between the ground and the root of the plant,
Measuring the voltage value V PC between the electrode P and the auxiliary electrode C when the measurement current is passed;
Dividing the measured the voltage value V PC at a current value I of the current for measurement seeking ground resistance R C of the auxiliary electrode C,
The radius of the auxiliary electrode C is a, the embedding depth is b (b >> a), and the radius L of the rod-shaped electrode (radius L, length D, L << D) having the same grounding resistance as the plant root is appropriately determined. The plant root evaluation method is characterized in that the equivalent length D of the plant root is calculated from the formula: ln (2D / L) / D = R R ln (2b / a) / (bR C ) .
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